Thermic telephone



ROBERT AERNOUT BARON VAN LYNDEN.

THERMIC TELEPHONE.

APPLICATION HLED OCT. 12, I917.

1,389,230, Patented Aug. 30, 1921.

IN VENTOR ROBE? THEE I007 FARM WW L Y/VOf/Y lav/g ATTORNEY UNITED STATES, PATENT OFFICE.

ROBERT AERNOUT BARON VAN LYN'DEN, F UTRECI-IT, NETHERLANIJS, ASSIGNOR, BY MESNE ASSIGNMENTS, T0 AMERICAN THERMOPHONE COMPANY, OF BOSTON, MASSACHUSETTS, A. OORI'ORATION OF MASSACHUSETTS. v I

THERMIC TELEPHONE.

Specification of Letters Patent. Patented A11 30, 1921 Application filed October 12, 1917. Serial: No. 196,254.

T 0 all whom it may concern:

Be 'it known that I, ROBERT AnRNoUT BARON VAN LYNDEN, a subject of the Queen of the Netherlands, and residing at Utrecht, in the Netherlands, have invented certain new and useful Improvements in Thermlc Telephones, (for which I have filed applications in Germany, December 23, 1916; Holland, September 15, 1916; and Norway, July 9, 1917,) of which the following is a specification.

My invention relates to improvements in thermic telephones and has for its object to provide means, whereby the mechanical manufacture of the heating-conductors of said thermic telephones is greatly facilitated.

According to my invention, I form the heating-conductors, by a helical coil of VVollaston wire or the like, the windings of which correspond to half the number of heating-conductor arcs connected in parallel. This coil preferably is flattened and with its ,central flattened portion inserted between two contact pins to which its windings are soldered or otherwise. fastened. In this manner, the bent portions of the windings project on either side of said pins so as to form a number of arc-shaped heating-conductors which are connected in parallel.

This heating-conductor device is, where Wollaston wires are used, immersed into an acid bath first with the wire arcs projecting on one side of the pins and then with those projecting on the other side, so that all the heat conductor arcs, whatever their number, may be etched to the desired length of sound emitters by only two manipulations.

If the two contact pins are fixed in an insulating block at one end, a very simple and solid construction for thermic telephones may be provided by inclosing the unit consisting of the insulating block, the contact pins and the heating-conductor arcs connected therewith, in a casing having a cover which is perforated to receive the free ends of said pins. Contact sleeves may be arranged over the free ends of said pins so as to be brought in engagement readily with a two pin plug to make connection with a cord or the like.

Reference is to be had to the accompanying drawings in which I have illustrated a preferred form of my improved arrangement in thermic telephones,

Figure 1 is a plan view and Fig. 1 an elevation of the contact pins fixed in aninsulating block, Fig. 2 is a side view of the heating-conductor device showing the wire coil in position on the contact pins, Fig. 3 is a plan view of the parts shown in Fig. 2, Fig. 4: is a sectional view of the heatingconductor device embedded in a casing and Fig. 5 is an elevation, partly in section, of the complete thermic telephone with connections. vi

The contact pins 1 are fixed at one end in an insulating block 2 and provided with collars 3 near their free ends. A wire coil 4, see Figs. 2 and 4:, is arranged between pins 1 and attached to them in any suitable manner, for instance by. soldering. This coil which is originally circular, as shown in Fig.

3 by dotted lines, is flattened, as illustrated in Fig. 3; The straight dotted lines 5 in this figure indicate the level up to which the arc-shaped portions of the heating-conductortcoil are exposed to the etching action of the acid bath.

The unit formed by the contact pins 1, the insulating block 2 and the Heatingconductors 4 is inserted in a cylindrical casing ti, see Fig. 1, which has a cover 7 made of insulating material. The free ends of pins 1 pass through perforations of cover 7 which abuts against their collars 3. The perforations are widened at their lower ends to receive contact sleeves 8 (shown detached in Fig. 4) into which the pins 1 project and in which contact pins such as 9 may be inserted. The upper end of cylinder 6 which is flush with the surface of insulating block 2, is closed by a perforated cap 10.

The entire thermic telephone is inclosed in a sleeve 12, as shown in Fig. 5, which is threaded at one end and engages a contact plug 11'also threaded and provided with contact pins 9, connected with a cord or other wire conductor attached to the said plug.

I claim: 1. In thermic telephones, a pair of parallel contact pieces, a support for holding said contact pieces in position, and a wire coil located between said contact pieces, with the axis of the coil parallel to said contact pieces, and each turn of the coil conductively attached to said contact pieces.

2. In thermic telephones, an insulating support, contact pieces secured thereto, and a wire coil located between said contact pieces and having its several turns secured to said contact pieces at opposite sides of the conductively connected with said contact pins, and a casing inclosing the unit formed bysaid contact pins, said insulating block and said wire coil, said casing being provided witha cover made ofinsulatingmaterial and having openings adapted to receive the free ends of said Contact pins.

4. In thermic telephones, a'wire coil, contact pieces located at opposite sides of said coil and extending,lengthwisethereof, and securedconductivelyto the several turns of the coil on the outer surface of the coil, and a support for saidv contact pieces.

5. In thermic telephones, contact pins provided with collars adjacent to one end, a support connecting saidpins at the other ends, and a wire coil locatedbetween said support and said collars, in contact with-said pins at its several turns.

6. In thermic telephones, a wire coil of oval cross section, contact pieces located at opposite sides of said coil and extending lengthwise thereof, and'secured to the several turns of the coil, and a support for said contact pieces.

7 In ther'mic telephones,a wire coil, contact pieces located at oppositesides of said coil, lengthwise thereof, and connected with conducting contact pieces extending lengthwise of said coiland engaging all the turns thereof at the same time.

9. In thermic telephones, a wire coil, and conducting contact pieces, insulated from one another but in engagement at all times with all the turnsof said coil.

1 l0. .Inthermic telephones, awire coil, conducting contact pieces insulated from each otherand extending lengthwise at opposite sides of said coil,and in engagement with the several turns of said coil, and asupport for said contactpieces.

' 11. In'thermic telephones,a wire-coil comprising alternate sections of etched and unetched .Vollaston wire, and contact pieces, insulated from each other and in engagement with unetched portions of said wire coil, at each turn thereof.

12. In thermic telephones, a Wire coil, and conducting contact pieces insulated from one another and engaging the several turns of said coilon its outer surface;

In testimony-whereofi l have signed this specification in the presence of two subscribmg witnesses.

ROBERT AERNOUT BARQN van LYNDEN.

Witnesses:

H. R. IIAGEN, F. W. LUTKI 

